scholarly journals Selfing species exhibit diminished niche breadth over time

2017 ◽  
Author(s):  
Daniel S. Park ◽  
Aaron M. Ellison ◽  
Charles C. Davis
Keyword(s):  
Niche Breadth ◽  
Niche Overlap ◽  
Mutation Accumulation ◽  
Accumulation Rates ◽  
Effective Population ◽  
Climatic Niche ◽  
Geographic Ranges ◽  
Outcrossing Species ◽  
Selfing Species ◽  
Over Time

AbstractSelf-pollinating plants (“selfers”) have larger geographic ranges and inhabit higher latitudes than their outcrossing relatives. This finding has led to the hypothesis that selfers also have broader climatic niches. It is possible that the increased likelihood of successful colonization into new areas and the initial purging of deleterious mutations may offset selfers’ inability to adapt to new environments due to low heterozygosity. Here, for the first time, we examine the climatic niches and mutation accumulation rates of hundreds of closely related selfing and outcrossing species. Contrary to expectations, selfers do not have wider climatic niche breadths than their outcrossing sister taxa despite selfers’ greatly expanded geographic ranges. Selfing sister pairs also exhibit greater niche overlap than outcrossing sisters, implying that climatic niche expansion becomes limited following the transition to selfing. Further, the niche breadth of selfers is predicted to decrease significantly faster than that of closely-related outcrossers. In support of these findings, selfers also display significantly higher mutation accumulation rates than their outcrossing sisters, implying decreased heterozygosity, effective population size, and adaptive potential. These results collectively suggest that while the release from mate limitation among selfing species may result in initial range expansion, range size and niche breadth are decoupled, and the limitations of an increasingly homogeneous genome will constrict selfers’ climatic niches and over time reduce their geographic ranges.

scholarly journals Balancing selection maintains ancient genetic diversity in C. elegans

2020 ◽  
Author(s):  
Daehan Lee ◽  
Stefan Zdraljevic ◽  
Lewis Stevens ◽  
Ye Wang ◽  
Robyn E. Tanny ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Balancing Selection ◽  
Model Organism ◽  
Environmental Response ◽  
Effective Population ◽  
Evolutionary Trajectory ◽  
Xenobiotic Stress ◽  
C Elegans ◽  
Outcrossing Species ◽  
Selfing Species

Summary paragraphThe mating system of a species profoundly influences its evolutionary trajectory1–3. Across diverse taxa, selfing species have evolved independently from outcrossing species thousands of times4. The transition from outcrossing to selfing significantly decreases the effective population size, effective recombination rate, and heterozygosity within a species5. These changes lead to a reduction in the genetic diversity, and therefore adaptive potential, by intensifying the effects of random genetic drift and linked selection6,7. Selfing has evolved at least three times independently in the nematode genus Caenorhabditis8, including in the model organism Caenorhabditis elegans, and all three selfing species show substantially reduced genetic diversity relative to outcrossing species8,9. Selfing and outcrossing Caenorhabditis species are often found in the same niches, but we still do not know how selfing species with limited genetic diversity can adapt to and inhabit these same diverse environments. Here, we discovered previously uncharacterized levels and patterns of genetic diversity by examining the whole-genome sequences from 609 wild C. elegans strains isolated worldwide. We found that genetic variation is concentrated in punctuated hyper-divergent regions that cover 20% of the C. elegans reference genome. These regions are enriched in environmental response genes that mediate sensory perception, pathogen response, and xenobiotic stress. Population genomic evidence suggests that these regions have been maintained by balancing selection. Using long-read genome assemblies for 15 wild isolates, we found that hyper-divergent haplotypes contain unique sets of genes and show levels of divergence comparable to that found between Caenorhabditis species that diverged millions of years ago. Taken together, these results suggest that ancient genetic diversity present in the outcrossing ancestor of C. elegans has been maintained by long-term balancing selection since the evolution of selfing. These results provide an example for how species can avoid the evolutionary “dead end” associated with selfing by maintaining ancestral genetic diversity.

scholarly journals Ecology of colonizing populations of the figfly Zaprionus indianus (Diptera, Drosophilidae) in Porto Alegre, Southern Brazil

2005 ◽  
Vol 95 (3) ◽  
pp. 233-240 ◽  
Author(s):  
Norma Machado da Silva ◽  
Carina da Conceição Fantinel ◽  
Vera Lucia da Silva Valente ◽  
Vitor Hugo Valiati
Keyword(s):  
Niche Breadth ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Survival Strategies ◽  
Porto Alegre ◽  
Zaprionus Indianus ◽  
Feeding Sites ◽  
Substrate Choice ◽  
Oviposition Substrate ◽  
Feeding Substrate

Ecological parameters such as trophic niche overlap and niche breadth were computed from the frequency of all drosophilid species collected in 2001 and 2002, in the urban area of Porto Alegre city, Brazil. Independently of place, drosophilids community composition and components breeding or feeding sites, the highest frequencies of Zaprionus indianus (Gupta, 1970) were obtained during seasons with higher average temperatures, especially during summer. From a total of the 19,146 individuals of Z. indianus sampled, 80% were found in this season. The data of trophic niche breadth suggest a higher opportunism of adult flies in feeding substrate use, but the females are still selective in oviposition substrate choice. For the values of niche overlap, only for some species, did we find any correlation between these and species richness and/or number of resources, and the most of the correlation values considering breeding and feeding sites were positive. The colonization of Z. indianus in Porto Alegre could be leading to adjustments in the survival strategies of the resident species, but it is possible that many species have conditions for coexisting with the invader.

scholarly journals Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake

2011 ◽  
Vol 9 (1) ◽  
pp. 169-176 ◽  
Author(s):  
Rodrigo Moncayo-Estrada ◽  
Owen T Lind ◽  
Carlos Escalera-Gallardo
Keyword(s):  
Niche Breadth ◽  
Temporal Distribution ◽  
Niche Overlap ◽  
Species Interaction ◽  
Trophic Relationships ◽  
Water Volume ◽  
Species Flock ◽  
Small Range ◽  
Mean Values ◽  
Significant Difference

Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium). Diets were described in critical shallow (August 2000) and volume recovery conditions (August 2005). Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia) and copepods (Cyclops). A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p < 0.0001) and sites at different years (MRPP analysis, A = 0.17, p = 0.004). According to niche breadth mean values, species were classified as specialized and intermediate feeders. In shallow conditions, the small range of niche breadth (1.72 to 3.64) and high diet overlap values (D = 0.64, L = 8.62) indicated a high potential for interspecific exploitative interaction. When the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96) and low niche overlap values (D = 0.53, L = 2.32) indicated a reduction of the species interaction. The Mann-Whitney U-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006). The increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution.

scholarly journals IDENTITY COEFFICIENTS IN FINITE POPULATIONS. I. EVOLUTION OF IDENTITY COEFFICIENTS IN A RANDOM MATING DIPLOID DIOECIOUS POPULATION

Genetics ◽  
1977 ◽  
Vol 86 (3) ◽  
pp. 697-713
Author(s):  
C Chevalet ◽  
M Gillois ◽  
R F Nassar
Keyword(s):  
Genetic Variability ◽  
Population Size ◽  
Effective Population Size ◽  
Random Mating ◽  
Matrix Multiplication ◽  
Inbred Lines ◽  
Inbreeding Coefficient ◽  
Effective Population ◽  
The Mean ◽  
Over Time

ABSTRACT Properties of identity relation between genes are discussed, and a derivation of recurrent equations of identity coefficients in a random mating, diploid dioecious population is presented. Computations are run by repeated matrix multiplication. Results show that for effective population size (Ne) larger than 16 and no mutation, a given identity coefficient at any time t can be expressed approximately as a function of (1—f), (1—f)3 and (1—f)6, where f is the mean inbreeding coefficient at time t. Tables are presented, for small Ne values and extreme sex ratios, showing the pattern of change in the identity coefficients over time. The pattern of evolution of identity coefficients is also presented and discussed with respect to N eu, where u is the mutation rate. Applications of these results to the evolution of genetic variability within and between inbred lines are discussed.

scholarly journals Monitoring the influx of new species through citizen science: the first introduced ant in Denmark

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8850
Author(s):  
Julie K. Sheard ◽  
Nathan J. Sanders ◽  
Carsten Gundlach ◽  
Sämi Schär ◽  
Rasmus Stenbak Larsen
Keyword(s):  
Exotic Species ◽  
Citizen Science ◽  
Niche Overlap ◽  
Botanical Garden ◽  
Sampling Effort ◽  
Niche Modelling ◽  
Climatic Niche ◽  
History Museum ◽  
Geographic Space ◽  
Citizen Science Project

Climate change and invasive species threaten biodiversity, yet rigorous monitoring of their impact can be costly. Citizen science is increasingly used as a tool for monitoring exotic species, because citizens are geographically and temporally dispersed, whereas scientists tend to cluster in museums and at universities. Here we report on the establishment of the first exotic ant taxon (Tetramorium immigrans) in Denmark, which was discovered by children participating in The Ant Hunt. The Ant Hunt is a citizen science project for children that we ran in 2017 and 2018, with a pilot study in 2015. T. immigrans was discovered in the Botanical Garden of the Natural History Museum of Denmark in 2015 and confirmed as established in 2018. This finding extends the northern range boundary of T. immigrans by almost 460 km. Using climatic niche modelling, we compared the climatic niche of T. immigrans in Europe with that of T. caespitum based on confirmed observations from 2006 to 2019. T. immigrans and T. caespitum had a 13% niche overlap, with T. immigrans showing stronger occurrence in warmer and drier areas compared to T. caespitum. Mapping the environmental niches onto geographic space identified several, currently uninhabited, areas as climatically suitable for the establishment of T. immigrans. Tetramorium immigrans was sampled almost three times as often in areas with artificial surfaces compared to T. caespitum, suggesting that T. immigrans may not be native to all of Europe and is being accidentally introduced by humans. Overall, citizen scientists collected data on ants closer to cities and harbours than scientists did and had a stronger bias towards areas of human disturbance. This increased sampling effort in areas of likely introduction of exotic species naturally increases the likelihood of discovering species sooner, making citizen science an excellent tool for exotic species monitoring, as long as trained scientists are involved in the identification process.

scholarly journals Wetland selection, niche breadth and overlap in 10 duck species wintering in northern Campania (Italy)

2018 ◽  
Vol 87 (2) ◽  
pp. 3-8
Author(s):  
Stefano Giustino ◽  
Marcello Bruschini ◽  
Elio Esse ◽  
Silvana Grimaldi ◽  
Danila Mastronardi ◽  
...  
Keyword(s):  
Niche Breadth ◽  
Selection Index ◽  
Niche Overlap ◽  
Campania Region ◽  
Duck Species ◽  
Wintering Area ◽  
Morisita Index ◽  
Species Preferences

Analysis of the selection index, the niche breadth and the niche overlap of 10 species of wintering ducks in 11 wetland areas of the Campania region between January 2003 and 2015 revealed that the distribution of the species in the examined sites was not casual. In fact, each species actively chose their wintering area. Using selection index, we were able to measure the species’ preferences and non-preferences for the 11 examined sites. By calculating Shannon-Wiener entropy and its normalized value (Evenness), we determined niche breadth; the Morisita index allowed us to check niche overlap.

Assessing the diet and trophic niche breadth of an omnivorous fish (Glanidium ribeiroi) in subtropical lotic environments: intraspecific and ontogenic responses to spatial variations

2019 ◽  
Vol 70 (8) ◽  
pp. 1116 ◽  
Author(s):  
B. C. K. Kliemann ◽  
M. C. Baldasso ◽  
S. F. R. Pini ◽  
M. C. Makrakis ◽  
S. Makrakis ◽  
...  
Keyword(s):  
Forest Cover ◽  
Agricultural Land ◽  
Niche Breadth ◽  
Intraspecific Variability ◽  
Niche Overlap ◽  
Trophic Niche ◽  
Main Channel ◽  
Size Classes ◽  
Intraspecific Variations ◽  
Environmental Variations

The diet of Glanidium ribeiroi was investigated in lotic stretches downstream from a cascade of reservoirs to determine how it responds to intraspecific and environmental variations. Monthly sampling was performed from 2013 to 2016 at sites including the main channel of the Iguaçu River and tributaries in preserved basins and agricultural land. The diet of individuals in the preserved tributaries was primarily associated with allochthonous resources, whereas in the non-preserved tributaries and main channel the diets were primarily associated with autochthonous resources. Trophic niche breadth and intraspecific variability differed significantly among sampling areas and size classes. Trophic niche overlap among size classes and sampling areas was low. Positive and negative relationships between the trophic niche breadth and the standard length of individuals were also found in different sampling areas. Intraspecific and ontogenic variations were strongly and consistently associated with forest cover. Individuals responded differently to local environmental variations due to differences in landscape gradients and life cycle changes. Therefore, the effects of spatial heterogeneity on diet composition and intraspecific variations therein appear to be crucial to the success of the populations evaluated. These results may help with the implementation of conservation measures for this and other endemic species.

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